A decrease of elastic strength of a contact segment of a female terminal has been measured by employing a thickness gauge after disengaging engaged male and female terminals accommodated in respective connectors or separately engaged male and female terminals.
One of such female terminal T.sub.1 is shown in FIG. 5 as a perspective view, wherein an electrically connecting portion 2 which engages with a mating male terminal is provided at one end of a base plate 1 and, at the other end of the base plate 1, there are provided conductor clamping segments 4 and insulator clamping segments 5 for a lead wire.
The electrically connecting portion 2 consists of side walls 6a, 6a raised from both sides of the base plate 1 and an upper wall 6b formed by bending inwardly the side walls to abut each other with their tip ends so as to form a square sleeve 6, and one extended end portion of the base plate 1 is folded back to form an elastic contact segment 7, the tip end of which is contacted with or placed in a proximity of the inner surface of the upper wall 6b.
By inserting a nose of a male terminal into the square sleeve 6 of the female terminal, the nose of the male terminal is pushed upward against the inner surface of the upper wall 6b by elasticity of the elastic contact segment 7 and the male terminal and female terminal T.sub.1 are electrically connected with each other by the elastic contact. However, the strength of the elastic contact segment 7 to push the male terminal is decreased in proportion to a time lapse if the elastic contact segment is pressed against the male terminal for a long period of time.
In order to measure the decrease of the elastic strength of the elastic contact segment, there have been two ways such that female terminals and male terminals are connected electrically in the same manner as in the actual use by engaging a female connector housing accommodating female terminals with a male connector housing accommodating male terminals or by engaging a single female terminal directly with a single male terminal to provide electrical connection.
A method of measuring the decrease of elastic strength of the contact segment is illustrated in FIG. 6A through FIG. 6C. As shown in FIG. 6A, by directing the nose of the male terminal T.sub.2 toward the front end of the female terminal T.sub.1, and inserting the nose of the male terminal T.sub.2 into the square sleeve 6 of the female terminal T.sub.1, the nose of the male terminal T.sub.2 is pushed upward against the upper wall 6b of the female terminal with the elasticity of the elastic contact segment of the female terminal T.sub.1, thus both terminals T.sub.1 and T.sub.2 are engaged with each other (see FIG. 6B).
Both terminals T.sub.1 and T.sub.2 are then heat treated by keeping the state of engagement and, in the next, the terminals T.sub.1 and T.sub.2 are disengaged. A gap formed between the elastic contact segment 7 and the upper wall 6b of the female terminal T.sub.1 is measured by inserting a thickness gauge (see FIG. 6C) for determining an amount of permanent deformation of the elastic contact segment 7 or the decrease of the elastic strength of the elastic contact segment 7 of the female terminal T.sub.1.
In such a conventional measuring method, it has been necessary to prepare a large number of male terminals T.sub.2 which engage with the female terminal T.sub.1 and, furthermore, it has been necessary to prepare the male terminals T.sub.2 having different thickness noses to evaluate an effect of permanent distortion of the elastic contact segment 7 to be caused by different thickness of the noses of the male terminals T.sub.2. Further, the thickness of the nose of the male terminal T.sub.2 must be tightly restricted in dimensional tolerances, this has resulted in a great difficulty in preparing the measurement of the permanent deformation of the electric contact segment.
In measuring operation, the conventional method of measuring a gap between the elastic contact segment and the upper wall of the square sleeve of the female terminal by employing a thickness gauge 8 lacks precision in measurement and has been inefficient.
It is therefore an object of the present invention to eliminate the problems encountered in the conventional method of measuring a permanent deformation of an elastic contact segment of a female terminal and to provide a method and apparatus for measuring a permanent deformation of the elastic contact segment of the female terminal with greater precision and high efficient by applying an optional amount of displacement onto the elastic contact segment of the female terminal.